· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Threaded   Pages: 1 astrobeast1 super member Reged: 09/28/10 Loc: leicester england sagitta volume calculation       #5717774 - 03/07/13 06:14 AM Edit   Reply   Quote Quick Reply   Hello to all, does anyone know of a source for calculating how much glass in volume is taken out from any given mirror blank when forming a sagitta =I am melting my own glass in preformed mould,s and wish to know if possible the weight of glass needed with some degree of accuracy. many thank,s Dan Post Extras:       Mike I. Jones Carpal Tunnel Reged: 07/02/06 Loc: Fort Worth TX Re: sagitta volume calculation [Re: astrobeast1]       #5717780 - 03/07/13 06:26 AM Edit   Reply   Quote Quick Reply   Volume of a spherical cap = (pi/3)(s^2)(3R-s) where s = sag, R = radius of curvature Mike Post Extras:       astrobeast1 super member Reged: 09/28/10 Loc: leicester england Re: sagitta volume calculation [Re: Mike I. Jones]       #5717785 - 03/07/13 06:37 AM Edit   Reply   Quote Quick Reply   thank,s mike, appreciate that=very quick ! was wondering if there,s a simpler method like a calculator which only requires an input of the diameter and the planned depth-thank,s Post Extras:       Mike I. Jones Carpal Tunnel Reged: 07/02/06 Loc: Fort Worth TX Re: sagitta volume calculation [Re: astrobeast1]       #5717792 - 03/07/13 06:47 AM Edit   Reply   Quote Quick Reply   Let r=D/2, then V = (pi/6)(s)(3r^2+s^2) Mike Post Extras:       astrobeast1 super member Reged: 09/28/10 Loc: leicester england Re: sagitta volume calculation [Re: Mike I. Jones]       #5717797 - 03/07/13 06:56 AM Edit   Reply   Quote Quick Reply   My maths aren't so good as your,s---did you suspect ? I will see if I can use both calc figures to my benefit. thank,s Dan Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 6 registered and 21 anonymous users are browsing this forum. Moderator:  ausastronomer, richard7  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 168 Jump to *Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Celestial Events*General Astronomy* -----   Beginners Forum   General Observing and Astronomy   Outreach   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Video and Electronically Assisted Astronomy*Astrophotography and Sketching* -----   Beginning and Intermediate Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   NEO   Planetary and Solar System Observing   Lunar Observing   Deep Sky Observing   Double Star Observing   Solar   Variable Star Observing and Radio Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Speciality Forums* -----   Arizona Science and Astronomy Expo   NEAF (Northeast Astronomy Forum) and NEAIC (Northeast Astro Imaging Conference)   AstroArt   Astronomy Clubs and Star Parties   Astronomy Software & Computers   AstroWebsites   Science! Astronomy & Space Exploration, and Others   Space Rocks   Stellar Media*Swap and Shop* -----   Shop and Swap Audio Components*CN Feedback and Vendor Announcements* -----   Vendor and Group Announcements*International Year of Astronomy 2009 - Forums are now closed.* -----   IYA Archive Info CN Forums Home

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